[PATCH] mm: simplify zone_idx()

[gaoxu]

store zone_idx directly in struct zone to simplify and optimize zone_idx()

Signed-off-by: gao xu <gaoxu2@xxxxxxxxx>
---
 include/linux/mmzone.h | 3 ++-
 mm/mm_init.c           | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 4c95fcc9e..7b14f577d 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -941,6 +941,7 @@ struct zone {
 #endif
 
 	const char		*name;
+	enum zone_type	zone_idx;
 
 #ifdef CONFIG_MEMORY_ISOLATION
 	/*
@@ -1536,7 +1537,7 @@ static inline int local_memory_node(int node_id) { return node_id; };
 /*
  * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc.
  */
-#define zone_idx(zone)		((zone) - (zone)->zone_pgdat->node_zones)
+#define zone_idx(zone)		((zone)->zone_idx)
 
 #ifdef CONFIG_ZONE_DEVICE
 static inline bool zone_is_zone_device(struct zone *zone)
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 9659689b8..a7f7264f1 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1425,6 +1425,7 @@ static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx,
 	atomic_long_set(&zone->managed_pages, remaining_pages);
 	zone_set_nid(zone, nid);
 	zone->name = zone_names[idx];
+	zone->zone_idx = idx;
 	zone->zone_pgdat = NODE_DATA(nid);
 	spin_lock_init(&zone->lock);
 	zone_seqlock_init(zone);
-- 
2.17.1